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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Development of In-plane Thermal Conductivity Measurement Method of Multi-layer Printed Wiring Boards Called Straight Fin Temperature Fitting Method

Get access (open in a dialog) DOI: 10.1615/IHTC15.eec.009396
pages 1971-1985

Resumo

We need experimental data of the in-plane thermal conductivities of multi-layer printed wiring boards (PWBs) as heat-spreading devices for a thermal design that improves the cooling capacity of electronic devices. Therefore we developed an in-plane thermal conductivity measurement method called straight fin temperature fitting (SFTF) method. The long, thin rectangular plate, which is horizontal on its long side, is used as a specimen and operated just like a straight fin by heating one end part and cooling the other. The in-plane thermal conductivity of the specimen is obtained by fitting the analytical axial temperature profile of the specimen plate to the measured temperature profile. In our development of this method, we first investigated the influence of the assumption of the heat transfer coefficient on the specimen surface as a constant in the analytical solution even though the heat transfer coefficient varies as a function of the surface temperature. We compared two types of analytical solutions with different boundary conditions for measurement accuracy and also experimentally investigated the measurement accuracy using standard metal plates of known thermal conductivities as specimens. Finally, we applied this method to measure the thermal conductivity of multi-layer PWBs. The following are our conclusions. (1) With the SFTF method, we obtained the in-plane thermal conductivity of standard specimen plates within almost ±10% dispersion in a range of fin efficiency from 0.2 to 0.8. (2) The inplane thermal conductivities of the multi-layered PWBs increased from 5 to 65 W/(m·K) in proportion to the bulk density, and the data were correlated within ±30% dispersion by a two-plate model with through holes as a function of the bulk density ratio by matrix density.